1. Field of Invention
This invention is directed to reformatting binary image data.
2. Related Art
Binary image data means that each pixel in the image data is a discrete value “1” or “0” representing either a black pixel or a white pixel. Documents to be converted into binary image data are typically continuous tone images. Continuous tone image means that the image is represented by various shades of color or various shades of gray. Various processes can be used to convert continuous tone image into binary image data, and yet give an impression of continuous tone image.
One such process, the halftoning process uses a mathematically stored screen pattern. The process systematically compares each pixel's continuous tone value with the value of the screen. If the continuous tone value of the pixel is less dense than the screen value, a white pixel is produced. On the other hand, if the pixel value is more dense than the screen value, a black pixel is produced. Simply stated, the process converts a gray scale image or a color image into binary image data, but gives the impression of multiple gray levels by producing more white pixels for a less-dense area and more black pixels for a denser area.
A specific type of halftoning process called error diffusion is an adaptive binarization process which has the property of preserving the local average gray level of the input continuous tone image. Specifically, error-diffusion propagates the error generated during binarization to neighboring pixels.